-
-
Re: Mysterious Exhaust Maifolds on eBay
The only aluminum V-8 manifolds that come to mind were used on the Pontiac Swiss Cheese cars. But I would not know what a Pontiac manifold looked like if it hit me in the head
Dick Whittington -
Re: Mysterious Exhaust Maifolds on eBay
348/409 bolt pattern???? mikeComment
-
Re: Mysterious Exhaust Maifolds on eBay
Mike-----
They can't be 348/409. Those engines used siamesed center ports (like small blocks). The only Chevrolet engines that have a similar exhaust port and exhaust flange configuration are big blocks. However, the seller says they are too long for big block. So, that pretty much means they are non-Chevrolet OR they were designed for use with some experimental cylinder head that never made it to production.In Appreciation of John HinckleyComment
-
Re: Mysterious Exhaust Maifolds on eBay
Whatever they fit, it certainly is an ill-conceived design. Consider that a typical spark ignition engine operating at high output shows EGT in the 1300-1500 deg. F range. Alumininum melts at 1221 deg. F, and most aluminum alloys begin to rapidly lose strength above about 400-450 F.
That's why aircraft designed to operate at sustained speeds above Mach 2 can't get away with aluminum as a structural material. Even the Mach 3.2 SR-71 circulated fuel around the leading edge surfaces to keep the titanium skin and structure temperatures below levels where titanium begins to lose strength.
If you've ever watched a full power dyno pull from off-idle to the redline you know that even after only 10-15 seconds the manifolds or header pipes go from cherry red to bright pumpkin orange.
The reason why aluminum heads don't melt is that the exhaust ports are surrounded by the cooling jacket and aluminum's low thermal resistance allows heat to rapidly transfer, which keeps the port wall that is exposed directly to exhaust gas heat considerably cooler than the exhaust gas itself.
The port walls rapidly heat up when exhaust gas is flowing due to the high convective heat transfer coefficient. Then they rapidly cool during the "dwell" period when exhaust gas doesn't flow, which is about three times longer. This allows the port walls to rapidly cool.
On a manifold the "log" and collector has high velocity hot exhaust gas flowing all the time, and it would take a very well designed cooling jacket to keep aluminum from melting.
DukeComment
-
Re: Mysterious Exhaust Maifolds on eBay
Pontiac.
Yes they did melt if used on the street, race only.Comment
-
Re: Mysterious Exhaust Maifolds on eBay
Perhaps they were manifolds designed for "intake" use, not exhaust. There were a number of experimental drag racing engines which used a reverse flow design, i.e. intake charge was blown into the normal exhaust ports, and exhaust expended out of the intake ports. I recall a Buick "nail head" engine for one, and that was for obvious reasons due to the valve layout (small exhaust valves and long port runners vs. larger intakes with short runners). Needless to say these engines had special camshafts to suit.
Stu FoxComment
-
Re: Mysterious Exhaust Maifolds on eBay
Used on Pontiac Super Duty cars, see info below. Not exactly the same as the Ebay post but they are aluminum and they do melt as I was told by a Pontiac guy.
I saw a set at a small swap meet a few years ago, picked one up and almost hit myself in the head with it. They sold for around $200.00 and the guy who bought them was reselling them for $2000.00
1963 Super Duty Aluminum Exhaust Manifolds (Part 1 of 2)
These particular exhaust manifolds are beyond rare.
GM Part # 9772521
GM Part # 9772522
They fit 980 SD heads only.
1963 Super Duty Aluminum Exhaust Manifolds (Part 2 of 2)
These particular exhaust manifolds are beyond rare.
GM Part # 9772521
GM Part # 9772522
They fit 980 SD heads only.Comment
-
Re: Mysterious Exhaust Maifolds on eBay
Pontiacs have the center two exhaust ports siamezed. If they are too long for a big block chevy I wonder if they're for some type of industrial application like an air compressor. The outlet position does not seem possible for installation in a car unless the pipe is going to make a tight turn. Chrysler hemis have spread exhaust ports, as do some Fords.Comment
-
Re: Mysterious Exhaust Maifolds on eBay
They look like BBF to me an FE.DFHComment
-
Re: Mysterious Exhaust Maifolds on eBay
PONTIAC.
1962 Pontiac Catalina
Comments: Pontiac expanded the availability of its Super Duty modifications in order to meet new NHRA rules changes which required engines and body parts for the stock classes to be production options on retail vehicles. Therefore, the very limited Super Duty 421 was officially listed as an expensive, limited option on fullsize Pontiacs. Fewer than 180 were built for 1962, with the majority installed in Catalinas, although about 16 were installed in Pontiac's new personal luxury coupe, the Grand Prix. The 1962 Super Duty 421 was officially rated at 405 bhp, but true output was rumored to be around 460 bhp. Although street legal, these engines were truly race ready with four-bolt mains, forged rods and crank, solid lifters, and NASCAR heads. Stock car racing versions used a single four barrel carb but street versions had twin Carter 500 cfm four barrel carbs and an aluminum intake manifold. Super Duty Catalinas also had free-flow cast iron headers with easily removable exhaust dumps that could be unbolted for even more power. Only three and four-speed manuals were offered; Pontiac's automatic couldn't handle the power. Other Super Duty options included aluminum front-end body clip and a weight-cutting modified frame. These modifications saved 110 pounds. Pontiac would even fit aluminum exhaust manifolds to save 40 more pounds, but warned that they were only intended for quarter mile competition as they would melt if they were subject to more heat.
Production:
Engines: 389 (2 bbl) V8 267 bhp. 389 (4 bbl) V8 333 bhp. 389 (3x2 bbl) V8 348 bhp. SD 389 363 bhp. SD 421 405 bhp @ 5600 rpm, 425 lb-ft @ 4400 rpm.Comment
-
Re: Mysterious Exhaust Maifolds on eBay
Norris,
I am not a Pontiac expert (not an expert on anything) the stuff I posted was found on Google.
Here is a picture of an aftermarket pontiac head which looks like the manifold I pictured would work on (the ones with the GM part numbers).
The manifolds in the Ebay listing don't look like they would fit, probably something other then Pontiac.
Edelbrock 60509 - Edelbrock Pontiac Performer/Performer RPM Heads
Comment
-
Re: Mysterious Exhaust Maifolds on eBay
The old Pontiac heads, including the Super Duty had the two center ports even closer than that, and just had a flat divider between them, maybe 3/16" thick. Some of the aftermarket headers only had 3 tubes with the center one flared at the top to accomodate both ports. I remember installing a set of Doug's on a friend's car, which were among the trickest back then, and they were full 4 tubes, but the center two were flattened on the inside to match up to the siamezed ports. I would have guessed they were some type of BBC if it wasn't stated they're too long for that pattern. Whatever they fit I think they're useless for anything other than a display engine.Comment
-
Re: Mysterious Exhaust Maifolds on eBay
I also thought Ford FE when I first saw the picture. The fact that the outlet points straight rearward eliminates any passenger car application I can think of. That flange would be nearly against the firewall. A medium or large truck application where the engine sits a fair distance from the firewall would allow a pipe to curve down with some clearance. They look almost like they would bolt to the intake side of the Olds 5.7 diesel or another V8 diesel.
TomComment
Comment